Yaskawa MP900 Series Ladder Programming Manual - Manual (Page 159)

5.5 Program Control Instructions
5.5.7 WHILE Construct (WHILE, END_WHILE)
5-90
( 4 ) Additional Information
[ a ] Applicable Conditional Expressions
The conditional expression for a WHILE instruction must be written with the format for an EXPRESSION instruction
to produce a Boolean (TRUE or FALSE) result. Numerical expressions that include substitution operators will not be
recognized.
∗ Refer to Appendix D Format for EXPRESSION Instruction for details on applicable instructions, operation order, and
notation conventions.
[ b ] Nesting Depth
The FOR, WHILE, and IF constructs can contain other constructs. This is called nesting. The maximum depth of a
nested structure that uses FOR, WHILE, and IF statements is limited to 8 levels.
If an instruction is preceded by a contact, it is treated like an IF construct and is included in the number of nesting lev-
els.
Expression Example Notation Remarks
MB000001 == true OK TRUE: 1 (ON)
MB000001 != false OK FALSE: 0 (OFF)
MW00002 < 100 OK −
MF00002 < sin(60.0) OK −
MW00001 == 0x00FF OK OK Prefix hexadecimal values with 0x.
MB000001 = true NG −
MW00001 = MW00002 NG −